The UK man arrested by London police this morning has been identified as Ryan Cleary, a 19-year-old who has already made headlines for irking the Anonymous collective.
Hacker group LulzSec, meanwhile, denied that Cleary was a major part of its operation.
According to The Telegraph, police arrived at Cleary's Essex home early Tuesday morning and took him to London for questioning. Thus far, the Metropolitan Police have only said they arrested a 19-year-old man "in a pre-planned intelligence-led operation" connected to recent hacks of businesses and intelligence agencies.
That led people to suspect he was part of the LulzSec hacker group, which has hacked Sony, Nintendo, and the CIA, among others. LulzSec, however, said Cleary was not part of its core group.
"Ryan Cleary is not part of LulzSec; we house one of our many legitimate chatrooms on his IRC server, but that's it," LulzSec tweeted recently. "We use Ryan's server, we also use Efnet, 2600, Rizon and AnonOps IRC servers. That doesn't mean they're all part of our group."
IRC stands for Internet relay chat, a chat room of sorts that also allows for private messages and file transfers.
LulzSec accused the UK police of being "desperate," and said officials arrested someone who is "at best, mildly associated with us." LulzSec asserted that the authorities "can't get us, so they're going after people they think might know us."
Cleary is also apparently mildly associated with that other well-known hacker group, Anonymous. In May, the Italian arm of Anonymous said on its blog that Cleary, a "fellow helper," had compromised its network.
"He decided that he didn't like the leaderless command structure that AnonOps Network Admins use.So he organised a coup d'etat, with his 'friends' at skidsr.us," Anonymous wrote. "Using the networks service bot 'Zalgo' he scavenged the IP's and passwords of all the network servers (including the hub) and then systematically aimed denial of service attacks at them (which is why the network has been unstable for the past week). Unfortunately he has control of the domain names AnonOps.ru (and possibly AnonOps.net, we don't know at this stage) so we are unable to continue using them. We however still have control over AnonOps.in, and will continue to publish news there."
Several days later, Anonymous posted Cleary's contact information and IP address on its anonops.blogspot.com blog with the title "Ryan Cleary Exposed!"
In a May interview with UK publication Thinq_, Cleary claimed responsiblity for the distributed denial of service (DDoS) attack and said he published the IP addresses of users visiting the site when he seized control. Cleary said he did it because he thought Anonymous had become too centralized, particularly during its ongoing campaign against Sony, and called the coalition's democratic, leaderless principles "bulls**t." He told Thinq_ that Anonymous was really led by a self-appointed group of 10 members.
Anonymous has not updated its Twitter feed or blog since Cleary's arrest.
Yesterday, LulzSec teamed up with Anonymous for Operation Anti-Security, in which both groups pledged to target government sites. They were successful in taking down the UK's Serious Organised Crime Agency's (SOCA) site, and there were reports that they also hacked the UK Census, but LulzSec denied it.
For more, see PCMag's Guide to Knowing Your Hackers and Did LulzSec Change the Hacking Game, or Just Get Lucky?